One of the most critical considerations in the successful treatment of bone tumors and infections is their detection and localization during surgery. Although nuclear medicine scanning techniques are a widely accepted and effective approach for imaging, they are very difficult to use in the tight confines of the operating room. This limitation is particularly important in the removal of a wide variety of bone lesions in which the infected tissue shows little or no anatomical abnormality. In virtually all of these cases, the difficulty in defining the boundaries of the lesions result in the removal of either too much or too little tissue and causes the attendant clinical consequences. Recent clinical experiments have indicated that a sensitive, hand held, nuclear probe could be of great assistance in localizing bone lesions during surgery. RMD, Inc. in collaboration with Queen's Medical Center and the University of Rochester Medical Center, proposes to do the research necessary to develop an extremely sensitive, miniaturized instrument for intra-operative bone scanning. This new hand held device will allow surgeons to accurately locate tumorous or diseased tissue during biopsy or resection and provide a very valuable technique for the successful treatment of this serious class of bone diseases.